For example, a compact card device (e.g., a memory card), which uses a mass storage flash device formed from a semiconductor material, is broadly used in recent years not only in a field of information processing apparatuses which process digital information, but also in various industrial applications such as in-car equipment mounted in vehicles. In particular, an SD memory card is one of the most popular card devices.
FIG. 27A is a schematic plan view of a conventional SD memory card. FIG. 27B is a schematic top perspective view of the conventional SD memory card. FIG. 27C is a schematic bottom perspective view of the conventional SD memory card. The conventional SD memory card is described with reference to FIGS. 27A to 27C.
The conventional SD memory card 900, which is used as a removable medium, typically has external dimensions of 32 mm×24 mm×2.1 mm. The SD memory card 900 is inserted into and ejected from a host device such as a personal computer in a first direction D1 (i.e., the longitudinal direction of the SD memory card 900). FIGS. 27A to 27C show a second direction D2 (i.e., the width direction of the SD memory card 900), which is orthogonal to the first direction D1, and a third direction D3 (i.e., the thickness direction of the SD memory card 900), which is orthogonal to the first and second directions D1, D2.
Definitions and terms about the aforementioned directions are commonly used in a series of the following embodiments. The definitions about the aforementioned directions do not in any way limit principles of a series of the following embodiments.
The SD memory card 900 includes a housing 910. The housing 910 includes a leading edge 911, which is inserted into the host device on ahead, and a trailing edge 912 opposite to the leading edge 911. The housing 910 includes recesses 940, which extend from the leading edge 911 toward the trailing edge 912, and ribs 914, which compartmentalize the recesses 940. Each of the ribs 914 which compartmentalize the recesses 940 also extends from the leading edge 911 toward the trailing edge 912, like the recesses 940.
As shown in FIGS. 27A and 27B, the SD memory card 900 further includes a single electrode array 920 arranged along the leading edge 911. The electrode array 920 includes electrodes 921 to 929 situated in the recesses 940, respectively. The electrodes 921 to 929 are aligned in the second direction D2.
The SD memory card 900 electrically communicates with a host device, which uses the SD memory card 900, via the electrode array 920. Therefore, data may be read from and written into the SD memory card 900.
Recent technical developments allow fast communication between the SD memory card and the host device. Consequently, it becomes faster to read and write data between the SD memory card and the host device.
Patent Documents 1 and 2 disclose a memory card having two electrode arrays. Since the SD memory card with the two electrode arrays has more electrodes than the SD memory card 900 described with reference to FIGS. 27A to 27C, such a SD memory card with the two electrode arrays may be suitably used for high frequency signal transmission.
If the SD memory card with the two electrode arrays disclosed in the Patent Documents and the SD memory card 900 described with reference to FIGS. 27A to 27C may be accommodated in a common housing space, the SD memory card with the two electrode arrays may become compatible with the SD memory card 900. However, since the SD memory card with the two electrode arrays has a different contact configuration from the SD memory card 900, an insertion distance of the SD memory card with the two electrode arrays into the housing space is different from an insertion distance of the SD memory card 900. In order to achieve compatibility with the SD memory card 900, a position of the trailing edge of the SD memory card with the two electrode arrays with respect to the housing space has to coincide with the trailing edge of the SD memory card 900 with respect to the housing space. However, because of the difference in the insertion distance between the SD memory card with the two electrode arrays and the SD memory card 900, a length of the SD memory card with the two electrode arrays has to be different from the SD memory card 900 in order to match the positions of the trailing edges with respect to the housing space.
The SD memory card with the two electrode arrays may not be inserted into a host device with a socket corresponding to a conventional SD memory card (e.g., the SD memory card 900 described with reference to FIGS. 27A to 27C), which has one electrode array. If the second electrode array from the leading edge is connected to a contact pin array of the socket in the host device, electrodes of the second electrode array has to be set to the same signal arrangement as the conventional SD memory card with the one electrode array. In this case, the first electrode array has to be used as additional electrodes for other signals. Accordingly, since the socket corresponding to the conventional SD memory card with the one electrode array does not correspond to the memory card with the two electrode arrays, appropriate electrical connection may not be established between the SD memory card with the two electrode arrays and the conventional host device.
Even if the conventional socket is improved and if the electrical connection for the first and second electrode arrays is established, it is necessary to switch signal wiring inside the SD memory card. Alternatively or additionally, signal arrangement of the first electrode array has to be switched to correspond to the conventional socket. Even on the basis of the aforementioned improvements, the high frequency signal transmission between the conventional socket and the SD memory card with the two electrode arrays may not be optimized. In order to switch the signal arrangement of the electrodes, it is necessary to connect a circuit, which is not required for high frequency signal transmission, inside the SD memory card, which results in increased floating capacitance of the signal electrodes of the SD memory card. Consequently, the signal transmission speed may not go up sufficiently.
Patent Document 1: JP 2006-252862 A
Patent Document 2: JP 2003-91700 A